But the rain in southern Florida resulted in a 1-category improvement to the D0-D1 there. D0 expanded in most states as 1-month rainfall deficits mounted, and D1 expanded in the Carolinas and Virginia. Soils continued to dry, with USDA reports indicating 50% of the topsoil moisture in North Carolina classified as short or very short (dry or very dry), with the value 48% for Georgia. To the north, a mostly dry cold front triggered showers over parts of Alabama to Virginia, but most of the Southeast region was dry this week. Rain earlier in the week, and Hurricane Ian late in the week, conspired to dump half an inch to locally over 5 inches of rain over the southern half of Florida. Improvement also occurred in New York, New Jersey, and Pennsylvania, although D1 expanded a little in southern New Jersey. The rain this week and previous weeks improved streamflows, ground water, soil moisture, and Standardized Precipitation Index (SPI) values, resulting in a broad one-category contraction of abnormal dryness (D0) and moderate to extreme drought (D1-D3) in New England. Most of the Northeast region received half an inch of rain or more for the week, with some areas experiencing over 2 inches. Drought and abnormal dryness expanded where it didn’t rain, including the Northwest, Great Plains to Mississippi Valley, and Mid-Atlantic states. Drought and abnormal dryness contracted where it rained in the Southwest, Northeast, and southern Florida. This is the third year in a row that a peak greater than 50% has occurred. Department of Agriculture (USDA), national topsoil moisture rated very short to short (dry or very dry) reached 54%, a high for the year to date and very close to the recent maximum of 56% achieved on October 18, 2020. The hot temperatures and continued dry conditions, especially in the South, further dried soils. The week ended up cooler than normal from the northern Plains to Northeast and into parts of the Southeast. Temperatures for the week averaged warmer than normal over the southern Plains to Lower Mississippi Valley and across parts of the Southwest and Northwest. The rain missed large parts of the West, which received little to no precipitation, and much of the Plains, Mississippi to Ohio Valleys, and Southeast to Mid-Atlantic states were drier than normal as well. The end result was a weekly precipitation pattern that was wetter than normal over parts of the West, southern Plains, Great Lakes, Northeast, and southern Florida. Monsoon showers joined in over the Southwest in these waning days of summer. The trough generated a storm track across the northern states, then sent a large cold front into the Southeast as the period ended. The high pressure ridge brought hot temperatures to the southern states at first, then to the West later in the period. Other players danced at the periphery – Hurricane Fiona moved across the Canadian Maritime Provinces, spreading rain over New England at the beginning of the week, while Hurricane Ian brought rain and wind to southern Florida as it bore down on the state just as the week ended. As they did a kind of do-si-do, the ridge swung from the southern Plains to the western CONUS. The other partner was a high pressure ridge. One partner of the pair was an upper-level low pressure trough which twirled from the West Coast to the northern Plains then migrated to the Northeast. Drought Monitor (USDM) week (September 21-27).
Two upper-level weather systems danced across the contiguous U.S.
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